Im using timelimit (android), which is FOSS, to impose time limits on myself, that works well, and it’s actually geared towards use for parents who want to control screen time. And I’m sure there’s ad blockers that have lists to achieve blocking of adult content, but don’t use those myself (I do use WG tunnel with pihole, which can do the same).

So, I think parental control should be quite easy to achieve?